Some photovoltaic installations may include a plurality of photovoltaic generators with their outputs connected to respective inverters to convert the generated energy into alternating current and, for example, to supply it synchronously to the electricity network. Depending on the time of day, geographical location, date, weather, etc., the incidence of sun on the panels of these photovoltaic generators may be low or very low, so that the efficiency of performance of the inverters may also be low. In some cases, the direct energy supplied by the generators (either current or voltage) may be below the minimum value acceptable by the inverter for it to start functioning. For this reason, the state of the art has proposed various alternatives for the energy optimization of photovoltaic generators, such as those based on switching of said generators to corresponding inverters, or based on the inclusion of additional, non-photovoltaic generators, with the aim of assuring energy supply.
U.S. Pub. No. 2008/0078436 discloses a system including arrays of solar panels, each one connected to a respective inverter. In order to guarantee energy supply when that coming from the solar panels is insufficient, the system includes an additional generator, in principle connected only to an additional inverter to collaborate in energy production. When the energy generated by the solar panels is very low or non-existent (at night for example), the additional generator connects to the inputs of the other inverters and increases their performance in a controlled way to substitute the panels in the generation of energy. The switching can be manual or automatic (for example, the system can be programmed to connect during the hours when the solar energy is very low). Said additional generator is “bio-friendly,” such as one which comprises a motor using biodiesel fuel. This application does not propose selectively connecting the additional generator to only some of the inverters that are connected to the solar panels or leaving the additional generator disconnected from its respective inverter when the solar panels are supplying sufficient energy.
JP2002073184 proposes a system for the generation of photovoltaic energy even when solar radiation is low. For that purpose the system, which comprises a plurality of rows of solar panels, each of which is connected in principle to a respective inverter, has switching units which, in their most simple operation, disconnect one of the rows of panels from an inverter (when the output energy is below the minimum requirements of the inverter) and connect it to another of the inverters. In other embodiments, the system includes a control unit which monitors the outputs of the inverters and makes predictions regarding said outputs, with the aim of reconnecting the disconnected inverter to its row of panels when this would be efficient.
In ES2284577T3 an installation comprising photovoltaic generators is proposed that, for an embodiment, are formed from photovoltaic modules connected in series for the supply of alternating energy after corresponding conversion by inverters. The installation includes a plurality of switching devices activated by a control device to initiate a switching action that causes the separation of at least one generator from a first inverter and a connection of this generator to a second inverter when a condition occurs in which the input power to the second inverter drops to such a low level that it no longer works in its optimum efficiency zone. The installation includes various generators and various inverters and the control device for the switching devices for disconnecting and connecting them according to the condition described.
Both JP2002073184 and ES2284577T3 propose disconnecting one or more photovoltaic generators from a first inverter to connecting them to a second inverter, either because the first inverter is working poorly or not at all efficiently (JP2002073184) or because the second inverter is working below its zone of optimum efficiency (ES2284577T3).
In none of these references is it proposed to provide additional photovoltaic generators, not previously connected to another inverter, for their selective and discrete connection to an inverter that can handle more input power than that being supplied by the photovoltaic generator to which it is connected, with the aim of complementing the supply of energy of said generator when it may be necessary or otherwise desired.